Solving Persistent ESP and ABR Issues on a 2008 MB S550
After many days and weeks of hunting down an ESP issue, initially pointing at faulty ABS wheel speed sensors and an ABR communication issue, I did the hard thing. I tracked all the ABS wiring and found some frayed wires, which I fixed. That resolved weird communication issues, and then I went and replaced all wheel sensors. I also sprayed brake fluid cleaner through the hubs, making sure there was no dirt, and had a chance to inspect the rear tone rings, which looked okay.
However, the ABS light-on problem remained, and I replaced the ABS pump and module attached to it. Then, the car would only intermittently pop up with an ESP error and disappear with no codes when scanning.
So I got a second ABS replacement module, and now the car complains about the traction control not working. No amount of relearning solved it. It’s yet another bad ABS module and maybe a pump.
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So, I am replacing the ABS pump for the third time. As they say, the third time is a charm. Luckily, the seller of the first ABS pump sent me a replacement. And… after properly bleeding the system for the third time, there are finally no errors.
Now, what is left with this car is 3-4 trans slips, but I’m guessing it’s because the transmission fluid has never been changed. Troubleshooting this issue took a long time, but I hope that helps those trying to resolve the dreaded ESP ABR issues. Always read the codes with a good scanner instead of throwing parts and money at the car. I could have saved a few hundred as my ABS wheel speed sensors probably didn’t need to be replaced as I found the hard way that those were not the issue.
